Retarding device for the delivery end of a printing machine



Jan. 14, 196 9 v BOISSELAU RETARDING DEVICE FOR THE DELIVERY END OF APRINTING MACHINE Filed June 23, 1967 United States Patent US. Cl.271--80 Int. Cl. B65h 29/20 ABSTRACT OF THE DISCLOSURE A retardingdevice for the delivery end of a printing machine for printing aflexible material such as paper in the form of a web or web-portion,comprising, upstream of a take-off station for sheets or sections ofsheets, a rotary take-up cylinder having retractable means forentraining the sections or sheets by their forward portions. Thiscylinder has at least one retarding element rotated in the oppositedirection from the cylinder and projecting periodically outside thecylinder periphery, in a predetermined angular position of the cylinder,and this retarding element co-operates in this angular position of thecylinder, with a rotary roller outside the cylinder, to retain thesections or sheets by their trailing portions.

The invention relates to a retarding device for the delivery end of aprinting machine.

In machines for printing a flexible material such as paper in the formof a web or web portion, printed sheets, or the sections formed bycutting and folding the printed sheets, are usually retarded bytransferring them from one rotary cylinder to another with a lowerperipheral speed. This retarding method may involve transfers to a thirdor even a fourth cylinder, the last retarding step being carried out bymeans of a drum into which the sections or sheets are projected by thelast retarding cylinder and from which they are extracted and releasedonto a machine delivery table.

If transfer of the sections or sheets is by means of grippers, thesegrippers are in front of the sections or sheets in the direction ofmovement, and retardation is substantially instantaneous. The trailingends ofzthe sections or sheets tend to approach the forward portions,causing crumpling if the step-down ratio between two cylinders is toohigh. This ratio is therefore limited in practice to approximately 35%.If transfer is by means of spikes, the difference in the peripheralspeed between two successive cylinders must be approximately 25% toprevent tearing;

A disadvantage of using a plurality of retarding cylinders is that theresulting device is bulky and expensive.

The object of the invention is to provide a retarding device in which asingle retarding cylinder gives step down ratios at least twice theusual ratios between successive retarding cylinders, without risk ofcrumpling or tearing.

The retarding device according to the invention has, before a take-offstation for sheets or sections of sheets, a rotary take-up cylinderhaving retractable means for entraining the forward portions of thesections or sheets, this cylinder has at least one retarding elementrotated in the opposite direction from the cylinder and projectingperiodically outside the cylinder periphery near and downstream of thetrailing edge of the sections or sheets, in a predetermined angularposition of the cylinder, and this retarding element cooperates in thisangular position of the cylinder with a rotary cooperating roller whichis outside the cylinder and whose peripheral speed is equal to 3,421,757Patented Jan. 14, 1969 "ice the residual tangential speed of theretarding element, to retain the trailing portion of the sections orsheets at this resultant tangential speed.

A retarding device embodying the invention is shown diagrammatically inthe accompanying drawings and will now be described, by way of exampleonly.

In the drawings:

FIGURES 1, 2 and 3 show the retarding device diagrammatically in three.successive positions, illustrating the begining of a retarding action,the retarding period and the end of the retarding action; and

FIGURE 4 is a transverse section on a larger scale through a cooperatingroller.

The retarding device has a take-up cylinder 1 with retractable spikes 2for entraining the front portions of sections 3. These spikes arecontrolled by known means (not shown).

The cylinder 1 carries two retaining elements consisting of bars 4mounted on two axes 5 parallel to the axis 6 of the cylinder anddiametrically opposite each other relative to this axis. The bars 4 areconstantly rotated in the opposite direction from the cylinder 1 byplanet gears 7 engaging a stationary sun gear 8, and by gears 9 keyed onthe bars 4.

Each bar 4 has a portion with a rounded outline 4a or a plurality offingers forming such an outline, which, with each revolution of the barproject a distance d outside the periphery of the cylinder 1, throughopenings 1a.

The step-up ratio is such that each of the two bars 4 carries out awhole number of turns about its axis 5 for each revolution of thecylinder 1. In the embodiment shown, with two bars 4, each of these barsturns twice about its axis 5.

Suitable selection of the distance E between the axes 5, 6 and of theeccentricity D of the rounded portions 4a relative to the pivot 5 givesat the top of these rounded portions-in their plane of alignment XX withthe axes 5, 6 (FIGURE 2)--a resultant tangential speed Va lower than thetangential speed Vb on the periphery of the cylinder 1, in apredetermined ratio such as 2:5, for example.

In the plane of alignment XX lies a co-operating roller 10 rotated inthe opposite direction from the cylinder 1 and having push rods 11supported on springs 12 (FIG- URE 4). The step-up ratio between thecylinder 1 and roller 10 is such that the tangential speed at the freeend of the push-rod 11 is equal to the resultant tangential speed Va.

Operation is as follows:

A section 3, shown at the top of FIGURE l, has been taken off apreceding cylinder (not shown) by the cylinder 1 and is entrained by thecorresponding spikes 2. Another section 3 is already engaged between thebar 4 and roller 10 and is being released by other spikes 2. Thetrailing end of this section, hitherto entrained at the peripheral speedVb of the cylinder 1, is then gripped near the plane XX by the roundedportion 4a and by the push-rod 11 of the roller 10 (FIGURE 2), and itsspeed is brought to value Va which will be its delivery speed (FIGURE 3)as it approaches the take-off station or possibly a takeoff drum (notshown).

The retaining action exerted on the trailing portion of the sectionkeeps the section taut and prevents it from crumbling when released.Since the rotating action does not occur until after the spikes releasethe section, there is no risk of tearing being caused by the spikes.

Obviously, the retarding device just described can be modified and anyuseful accessory may be added to it without exceeding the scope of theinvention. For example, the take-up cylinder may be adapted to take up alarger number of sections or sheets and carry a larger number of rotaryretaining elements, associated with a single cooperating roller or withtwo co-operating retaining rollers acting alternately. Also, theretarding element, instead of having one portion projecting periodicallyfrom the takeup cylinder, could be a cylinder whose periphery constantlyprojects.

What I claim is:

1. A retarding device for the delivery end of printing machines forprinting a flexible material such as paper in the form of a web or webportion, characterised in that it has, before a take-01f station forsheets or sections of sheets, a rotary take-up cylinder havingretractable means for entraining the forward portions of the sections orsheets, this cylinder has at least one retarding element rotated in theopposite direction from the cylinder and projecting periodically outsidethe cylinder periphery near and downstream of the trailing edge of thesections or sheets, in a predetermined angular position of the cylinder,a rotary cooperating roller, and this retarding element co-operates inthis angular position of the cylinder with said rotary co-operatingroller which is outside the cylinder and whose peripheral speed isequalto the residual tangential speed of the retarding element, to retain thetrailing portion of the sections or sheets at this tangential speed.

2. A retarding device as claimed in claim 1, characterised in that eachof the retarding elements carried by the cylinder is inside the cylinderand is rotated about an axis parallel to the cylinder axis by means of aplanet gear carried by the cylinder and engaging continuously with afixed gear coaxial with the cylinder.

3. A retarding device as claimed in claim 1, characterised in that oneach of the retarding elements carried by the cylinder an eccentricportion periodically projecting outside the cylinder periphery has arounded outline whose generatrices are parallel to that of the cylinder.

4. A retarding device as claimed in claim 1, characterised in that onsaid rotary co-operating roller outside the cylinder the retainingelement which cooperates with the retarding elements carried by thecylinder to retain the trailing portion of the sections or sheets issubject to a resilient member which urges it to bear on the sections orsheets.

References Cited UNITED STATES PATENTS 2,067,565 1/1937 De Manna 271-80RICHARD E. AEGERTER, Primary Examiner.

